# Understanding Secure Authentication

ADC offers two types of password authentication and the option of using Secure Sockets Layer (SSL) encryption. The two types of password authentication offered are:

- Basic (Clear Text) sends the password and the message over the network unencrypted.
- Windows Challenge/Response does not transfer the password over the network during authentication, and other authentication information is transferred unencrypted.

Applying SSL encryption to either type of authentication determines if the entire transaction session is encrypted. If you are replicating to a server that is located outside of your organization, you should use SSL encryption. If you choose Basic (Clear Text) authentication with SSL, all authentication information transferred over the network is encrypted. Choosing Windows Challenge\Response with SSL encrypts authentication information that is transferred over the network.

Note

Data replicated using SSL encryption must be encrypted before being sent and then unencrypted by the receiving server before it can be added to the destination directory. These additional operations slow replication performance somewhat.